The NVV Auger electron spectrum of the HI molecule

The electron-beam-excited NVV Auger electron spectrum of HI is presented together with a new recording of the X-ray excited photoelectron spectrum of the I 4d core lines. It is shown that the initial I 4d core hole state is vibrationally excited. The NVV Auger electron spectrum is dominated by transitions to the pi -2 dicationic states of 3 Sigma - , 1 Delta and 1 Sigma + symmetry. Vibrational structure is resolved in all Auger transitions and the equilibrium geometry of both the initial core-hole state and the final dicationic states have been determined. A splitting of the 3 Sigma 1 - and 3 Sigma 0 - states of 220 meV is observed. The dissociation of the pi -2 dicationic states in terms of Coulomb explosion is discussed and tentative potential curves are given.